A telephone connected to a land line has a direct relationship between a telephone number and a physical location, which is maintained by the telephone company and available to emergency responders via the national emergency response service centers in form of emergency subscriber lists. When an emergency call is received by a center the location is automatically determined from its databases and displayed on the operator console.

While it doesn't offer as many features as its business-class version, residential VoIP is still overwhelmingly attractive when compared to standard phone service; firstly because of its much lower overall price tag and second because it simply offers more features than an old fashioned long line. You can keep your current number, suffer zero restrictions when it comes to 911 or long-distance calling, drop your monthly price to a low fixed number, and take advantage of VoIP-only features like smart call routing, virtual numbers, and more.
It gets even better! Calling internationally using VoIP is far less expensive than using a traditional landline phone company. Every region of the world, from Afghanistan to Zimbabwe, has its own combination of technological development, geographic obstacles, regulations, and taxes. Cell phone carriers, much like VoIP providers, have their own network, which is why it usually costs more to call international cell phones. If a VoIP provider has a significant presence in a country, it’s likely that landline calls will be unlimited with an international package. For example, if you are using Vonage Word, calling from the U.S. to a landline in Germany is included, but it costs US$.0061 per minute to call a cellular phone. If you are using ViaTalk World, you can call both German cell phones and German Landlines for the same rate – free up to 1200 minutes per month. Don’t forget that with every VoIP provider, if you call within their own network, calls are always free no matter where you are in the world. With the development of SIP, you can easily make and receive free international calls from your home using VoIP.

Setting up a residential VoIP system can mean big savings on your phone bill, especially if you make a large number of long distance and international calls. In addition, these systems are mobile-optimized, and provide a wealth of features that may just change the way you think of your home phone service. Take a look at the features you need and the budget you can handle, and make the decision that’s right for you.
On the early ARPANET, real-time voice communication was not possible with uncompressed pulse-code modulation (PCM) digital speech packets, which had a bit rate of 64 kbps, much greater than the 2.4 kbps bandwidth of early modems. The solution to this problem was linear predictive coding (LPC), a speech coding data compression algorithm that was first proposed by Fumitada Itakura of Nagoya University and Shuzo Saito of Nippon Telegraph and Telephone (NTT) in 1966. LPC was capable of speech compression down to 2.4 kbps, leading to the first successful real-time conversation over ARPANET in 1974, between Culler-Harrison Incorporated in Goleta, California, and MIT Lincoln Laboratory in Lexington, Massachusetts.[71] LPC has since been the most widely used speech coding method.[72] Code-excited linear prediction (CELP), a type of LPC algorithm, was developed by Manfred R. Schroeder and Bishnu S. Atal in 1985.[73] LPC algorithms remain an audio coding standard in modern VoIP technology.[71]
(e) In India no Separate Numbering Scheme is provided to the Internet Telephony. Presently the 10 digit Numbering allocation based on E.164 is permitted to the Fixed Telephony, GSM, CDMA wireless service. For Internet Telephony the numbering scheme shall only conform to IP addressing Scheme of Internet Assigned Numbers Authority (IANA). Translation of E.164 number / private number to IP address allotted to any device and vice versa, by ISP to show compliance with IANA numbering scheme is not permitted.
It is much cheaper than a regular landline - most providers offer unlimited calling plans (including long distance) in the USA and Canada for under $10 per month. There are also some great promotional deals available such as 2 year specials that cost around $6 per month (includes all your calling). Comparing this to a regular PSTN (landline) phone service that can cost in the region of $60 per month can result in savings of over $500 per year for many home phone users. If you also regularly call International numbers you can save even more, with rates typically starting from around 1 to 2 cents per minute to many countries.